Enery Transfer Flashcards
How do plants use sugars
- primarily as respiratory substrates
- synthesis other biological molecules eg cellulose
What is biomass
Total dry mass of tissue or mass of carbon measured over a given time in a specific area
Units for biomass
When an area is being samples: gm-2
When a volume is being sampled: gm-3
How u can’t ensure all water is removed from an sample
Heat the sample and reading it until the mass reading is constant
Define gross primary production
Total chemical energy in plant biomass within a given volume or area
Define net primary production
Chemical energy store in plant biomass after respiratory losses to the environment
Mathematical equation timing NPP and GPP together
NPP = GPP - R ( respiratory losses)
What is NPP available for
- Plant growth and reproduction
- other tropic levels in the ecosystem eg herbivores and decomposers
How can biomass be measured
In terms of mass of carbon and dry mass of tissue per given area
Method to measure biomass
- sample of organism ride in an oven set at low temp (avoids combustion)
- sample reweighed at egular intervals
- all water removed when mass remains constant
- mass of carbon taken to be 50% of dry mass
Why is dry mass more representative
Water content of maples varies
How can chemical energy stored in dry biomass be estimated
Using a calorimetry
- sample of dry mass burnt
- energy released is used to heat a known volume of water
- change in temp of water used to calculate the chemical energy
What 3 groups are organism divided into
- producers
- consumers ( primary, secondary tertiary)
- saprobionts (decomposers)
Why are orangisms divided in to groups and what is it based of
How they obtain their energy and nutrients
What are tropic levels
Energy flows from primer producers to consumers
What is lost with each trophic level
Energy
What it’s is biomass measured in
- dry miss per given area in given time
- area of grassland per square metre/gm-2
- for volume grams per cubic metre gm-3
Problems with measuring dry mass
- all organisms must be killed
- only a small sample can be taken may not be representative
How can energy from burnt biomass be calculated
E = charge in temp/ specific heat capacity + volume
What is NPP used for in plants
- plant growth and reproduction
Explain why length of food chains is limited
Energy is lost at each trophic level
Insufficient energy to support higher trophic level
Why is most of the sun energy not converted to organic matter
- most solar energy is absorbed by atmosphere or reflected by clouds
- photosynthetic pigments cannot absorb some wavelengths of light
- not all light falls directly on a chlorophyll molecule
- energy lost as heat during respiration/photosynthesis
How can net reduction of consumers be calculated
N = I - (F+R)
I : chemical energy from ingested food
F :energy lost as faeces and urine
R: respiratory losses
Why does biomass decrease long the food chain
- energy lost in nitrogenous waste (urine) and faeces
- some of the origins is not consumed
- energy lost to surrounding as heat
What is primary ad secondary productivity
- Rate of primary or secondary production
- biomass in a specific area over a given time period eg Kj ha-1 year-1
Common farming practise and how they increase efficiency of energy transfer
- exclusion of predators: no energy los to other organisms in food web
- artificial heating: reduce energy lost to maintain constant body temp
- restriction of movement : les energy lost in muscle contraction
- feeding controlled at the optimum : more growth less waste
Equation for efficiency
Energy converted to a useful form (J) x 100/ total energy supplied
Why do most food chain only have 4-5 trophic levels
Inefficiency of energy transfer means
- insufficient energy available to support a large enough breeding population a tighter TLS
- biomass less a tighter TLS
- total amount energy available les at each TLS
